No single solution to increase endangered Monarch butterfly population, says expert

Planting more milkweed and rearing monarch butterflies could help dwindling populations, but there are bigger issues with the endangered species.

The reasons for the declining trend in the monarch butterfly population is spread across three different countriesMexico, the United States and Canada, said Stephen Heard, a biology professor at the University of New Brunswick.

"There is almost never a single magic bullet, there are several different things you might have to do to make sure we always have these super-cool butterflies with us," he said.

He said the monarch butterflies roost together in about a dozen "very small" overwintering areas in central Mexico, which makes them vulnerable to both bad weather events and human disturbance.

WATCH | How milkweed gardens can help monarchs:

Milkweed gardens can help declining monarch populations

2 months ago

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New Brunswickers who plant milkweed gardens can help preserve monarch butterfly population, says biology professor Stephen Heard.

Heard said some butterflies that move northfeed on milkweed and die due to the use of pesticides in fields. "These are things that are almost entirely our fault."

He said a lack of milkweed the only food source for monarch caterpillars is also due to the change in land use. These plants get cleared out of fields, ditches and pond edges making it impossible for monarch larvae to find nutrition, said Heard.

"If we don't have milkweed, we don't have monarchs."

The annual survey published in February by the World Wildlife Fund (WWF) and its partners indicated that the eastern migratory monarch butterflies occupying the overwintering areas in Mexico experienced a significant decline.

"The new data indicates that the species occupied only 2.2 acres during the 2023-2024 winter season, 59% less than the previous year when scientists observed 5.5 acres.," stated the WWF survey.

New Brunswickers in action

Many municipalities in New Brunswick have milkweed plants or gardens trying to help the young caterpillars prepare for their more than 4,000-kilometre overwintering journey to Mexico.

The city of Dieppe recently opened its second milkweed garden near its Aquatic and Sports Centre parking lot. A press release noted that the caterpillars can eat up to 200 times their body weight in milkweedbefore turning into monarch butterflies.

"It was important for us to recognize the role that municipalities can do in protecting endangered species," said spokesperson Alexandre Truchon-Savard.

He said an environmental group called Les Ami.e.s de la nature du sud-est du N.-B., reached out to the city to plant their first milkweed garden on Surette Street last year.

The same group partnered this year and planted the sports centre parking lot garden in late July. Only this time, the city added an artistic sculpture and information plaques to the area.

"We wanted to take an active part in protecting this important species," said Truchon-Savard.

Rhal Vienneau, a member of Les Ami.e.s de la nature du sud-est du N.-B., is locally known as the "butterfly man" for his passion for raising monarch butterflies.

Vienneau said he used to raise and release about 400-500 monarchs every year, but has now downsized to a couple hundred, due to time constraints.

"I am lucky I have a place to do it, so I do it for pure enjoyment," said Vienneau who has been raising monarchs for about two decades.

He said a majority of caterpillars in the wild fall prey to predators. Also, if the milkweed is planted too close to each other it becomes home to several insects that prey on the monarch butterflies and caterpillars, he explained.

"My estimate would be probably 80 per cent of those small caterpillars don't survive."

Vienneau said although he raises the butterflies in the safest possible manner, he does not promote the practice, as one has to have certain expertise to look after the different delicate life stages of the insect.

He said raising monarchs does not have a negative effect on the population, but is not the best solution to increase the numbers.

A three-country effort

He said the real solution is to plant milkweed and nectar plants all along the butterflies' migratory route from Mexico. This will give themenough nutrition throughout their journey.

"Rearing butterflies will have a minimum effect ... so it is better to just plant milkweed and spread the milkweed in different places," said Vienneau

According to Heard, a combination of planting milkweed, raising monarchs, avoiding the use of pesticides, and reducing habitat lossall go hand-in-hand, he said.

"If we all raise monarchs in our yards, that won't help at allif the overwintering sites in Mexico get clearcut," said Heard.

He said individuals raising monarchs may notmake a huge dent, but it may have an impact over time.The same goes for planting milkweed and maintaining habitat.

"If everyone takes a little step themselves, then we have got a good place," said Heard.

"It is headed in the right direction in terms of societies caring about it ... it is very difficult to predict what happens."